http://i67.photobucket.com/albums/h3...55-Graph-5.jpg

Hard to ride, yes. But you are talking HRC's best efforts to make 70+hp, that's like thinking since you bought the new Camero that you can call Hendrick Racing and have them give you the Jimmy Johnson Special.

As far as a tune, still going to need to get the settings right to make peak power, just the 4 stroke won't run as bad when it has a bad tune.

As far as mileage, thus far in sleds, jetskis, and outboard engines, the newer 2 strokes produce less emissions, are cleaner buring, and are substancially higher in mileage (more effecient, makes power every cycle of the engine, vs. every other on the 4-stroke). The 600 E-Tec Ski Doo has people getting almost 80% increase in mileage vs. the previous 600 2 stroke, and it is over 100% more than the closest 4-stroke. 200-220 miles on 9 gallons is getting to be common.

I'll take less stuff to break (less parts) and lighter weight (less parts) anyday.

That SkiDoo engine sounds fantastic (direct cylinder injection?) but those ^^ are all motorsports innovations that won't translate to model engines in scale or economy.

Some of the limiting factors in model engines for cars are very limiting.

That may be true. But, probably over $10 grand in high performance parts to make that power. Little bit of work and a 500cc 2-stroke will make same power and not as much money either. That is why a Factory race bike to build now is 60-100 thousand dollars if you had to build one.

Is it harder/easier to tune a 4 stroke motor? Never owned one before but if they are easier to tune then there is a possibility we may see this in the future.

24MPG on the water?

Not gonna happen buddy. Sorry.

Before you claim BS, I live not 2 min. from Lake Erie. I have friends with Etec 600 Skidoos and they are LUCKY to get 10MPG.

My 18Ft 305 powered Bayliner gets about 5 on a good day. 3 If I keep my hand in the throttle. 120Gal Bunkers.

those numbers mite be a bit much now dnt u think, u may be able to get 63~66 hp out of a 500 but at those numbers it would be so jerky n hard to ride. the most hp stock is the ktm450 sxs with 56 out of the box, that was the first 450 i ever raced n it was over seas when i was 16 in 05 and it was so fast i could barely hold on, i got lapped by everts haha not funny then but it is now. we had a honda built buy varner n had 62 hp, but it was a ridable 450.

if anyone built a 4 stroke right now for rc it probly wouldnt be affordable by anyone who was in this for fun, u mite see some people in the intermediate class shelling out for one n probly a lil more in the pro classes but lets get real these engine manufactorors only want to build something thats gonna sell n those intermediate n pro drivers more then likly have decent hookups, so really there looking for the sportman drivers n bashers to buy this engine, what would u sportman drivers buy? a 150 dollar engine or 200 werks engine or a 400 dollar 4 stroke ( if its even that cheap ) engine. it wouldnt make money n thats what companies look at first. no doubt in my mind a 4 stroke would be better n it would last longer n fuel mileage would b a huge gain but facts r its way to much money to design one made for rc then ask for a ton of money for it n expect it to sell, look at the grossi liguid cooled engine, i wish i could have one but 550$+ bucks get real im in this for fun.

now a conversion kit to make a plane engine work mite be a better product to design n sell to the rc car world.

I think he means snowmobiles, the water guys don't measure in miles do they?

I don't, some do. Still not gonna get 24MPG on a 2 stroke sled either LOL.

No harder to scale down than a 5 valve cylinder head with titanium valves.

Direct Cylinder Injection was introduced into sleds over 10 years ago with Arctic Cat on the 98 ZR580 platform.

The current Rotax version places the injector directly on top of the head, that's why they are so clean. They dont inject any fuel underneat the piston at all. All that is moving in the crankcase is air and 2 small oil injectors that lube the lower rod bearing. People are reporting over 2500 miles on one gallon of oil. IMO, the technology could easily be transferred over to a R/C engine with ease. But as a manufacturer, why would you bother? They sell so many of these engines (with about a 300% profit), why re-tool and do something different?

Where are you going to add the electric fuel pump needed to make the 3000PSI Injectors DI uses? Where are you going to add the oil tank and pump?

24mpg on a Snowmobile, not a JetSki

http://www.sledmagazine.com/actions/...91214193931639

And I Quote "About consumption, we can only be satisfied by the average consumption of 21.83 MGP for more than 4 000 miles. With peaks at 27.5 MPG, we can really talk about a fuel economy machine"

Much harder than it seems but the volumes in the hobby industry are microscopic compared to full size motorsports. I hear they have basic fuel injection for planes but they require another separate power source and other complexities that wouldn't play well with RC car dirt or economy.

The same place you would have to put the overhead camshafts and variable timing in order to make big numbers with a 4-stroke

The same place you are going to have to keep a dry-sump oil lube system and oil tank on the 4-stroke

See, I have been building race snowmobiles for over 20 years, have seen allot of so called "technology" come and go, and about 95% of the hype is just that. Hype.

In Drag Racing, yes, the 4 stroke is king. Cause they can bolt on a 30+ PSI turbo on it with a intercooler on it that is as big as a BBQ grill, and yea you can make 450+hp on a reletively "stock" engine. But you could NEVER use it on the trail or the mountains (unless going strait)

The whole sled industry got snowballed (me included, I bought a RX-1, what a over-rated POS) when the 4-Stoke sleds came out. Weighs 200+lbs more, and makes less HP and Torque, all at a 40% price increase.

Turns out to be, that a guy could buy a 700-800cc 2 stroke sled, bolt on a smaller 14-16psi turbo with no intercooler, and makea easy 240hp sled that can climb with anything making more, caust it doesnt have to haul around all the extra weight to do it. All with less stuff to break and go wrong.

I jumped on this topic because I think allot of people have the wrong mis-conceptions and what technology really could be doing for us.

If I had the money, I would love to take on the challange and build a .21 sized EFI with a powervalve, but I have to make a living.

The R/C industry won't do it, they are making too much money on it now.

Food for thought - Most of these manufacturers make a 3, 5, 7 port versions of their engines. And consider a average 3 port costs , $230? Then take their top of the line 7 port, $500? Do you think it takes another $250+ dollars to make that engine? NO! Maybe another $10 in machining time. Thats it.

WTF are you talking about? When did we go from 1/8 scale cars to full-on race bikes and sleds? RC 4 strokes need no oil injection. Move to DI and you now NEED Oil injection as the fuel/lube mix isn't moving through the engine, IN AN RC APPLICATION.

And I'm sorry, simple Hot rodding can almost double the output of a 4 stroke motorcycle engine. Jets, Exhaust, timing curve and camshafts. In that order.

The big difference IN AN RC APPLICATION between 2 and 4 stroke are thus:
2 stroke needs 20K+RPM to produce peak power, some to 40,000.
4 strokes produce at about 1/2 that RPM.

1/2 the RPM means 1/2 the fuel used for the same displacement at a given power level.

4 strokes are easier to tune
2 strokes are lighter

2 strokes have "toggle switch power" On or off.
4 strokes have a more linear torque curve, meaning applying that power should in theory be easier.

2 strokes need smaller gearing to use the 20K+ RPM where the power is.
4 strokes could use 1/2 that gearing(higher) to achieve the same power to the ground.

Remember we are talking GLOW RC ENGINES. Not spark ignition engines. Remember these are all 2 and 4 stroke DIESELS, not spark ignitions. Enough residual heat must be retained in the glowplug to ignite the fuel mixture. Kinda hard to do with an injector squirting fuel in just before TDC, cooling the piston and head.

2 stroke model engines dominate because of 3 factors.
Ease of production
Simple design
excellent power to weight ratio.

4 strokes always have been a novelty in the RC world, much like radials, Wankels, twins, triples, quads and pents.